Review By: Lee Copeland
09/17/2003The Robertsons define systems analysis as "the craft of understanding systems by building models of them" (130). This book describes the various models used in classical structured analysis and how to create them. Specifically, the models described are:
- the context diagram that describes the system boundaries; i.e., what is inside the system and what is outside
- data flow diagrams that describe the system processes and the flow of data between those processes
- the data model that describes the key data entities and their interrelationships
- the data dictionary that provides a precise definition of the system's data
- event-response models that describe the external events that trigger the system and the system's response to those events
- mini specifications that define each functional process in sufficient detail for designers and programmers

Not only is each of these models defined in detail, the authors lead the reader through the process of constructing these models. The book uses an excellent case study throughout: The Piccadilly Project, which involves the sale of air time for commercials during television broadcasts. It is explained in great detail so that the reader can readily understand it, yet it is complicated enough to illustrate the analysis techniques, challenge the reader, and lead to a higher level of understanding and skill in analysis.

In addition, the authors use a large number of entertaining and informative examples to illustrate key analysis concepts: Woolly Mammoth Hunting, Buzzcott Employment Agency, Fastbuck Book Company, West Ashling Duck Race, Miss Tweedy's Dating Service, and many others.

The authors also explain the importance of modeling not only the essential system but also the physical systems, both current and future. The essential system is the "perfect" system. which includes only the system requirements and excludes anything having to do with how the system will be designed or implemented. The physical system must take into account the hardware and software environment in which the essential system will be implemented.

One difficulty that all authors face is how to match the linear flow of a book to the many and varied interests and experiences of their readers. The Robertsons have invented a very clever approach to guiding different kinds of readers through their book—Ski Trails. Modeled on the grading of ski trails (beginner, intermediate, expert) the authors have created four separate paths through their book depending on the prior knowledge of the reader and the goals for reading the book. Given these trail descriptions, readers can choose the parts of the book that are most useful to them.

Finally, the authors offer a bit of very wise advice to analysts who don't have all the information they need: "You analyze systems—you don't invent policy nor do you guess it" (31).

I highly recommend this book to all those who want to increase the ability to perform complete systems analysis.